of brooklyn



A pr. 24, 1923. 1,452,850

1 SCHMIDT TELEPHONE APPARATUS Filed June 26', 1922 translating,- coil.spool..

Patented Apr. 24, 1923.

UNITED `STixTES iasasse PATENT OFFHCE.

LAMBERT SCHMIDT, OF BROOKLYN, NEWT YORK, ASSGNOR T RAITVE CItPORlt-TION, OF BROOKLYN, NEVT YORK, A CRPOHJNFIGJBT F NETW YORK.

TELEPHONE APPARATUS.

Application filed June 26, 1922.

To all wiz/0m it mcjz/ concern Be it known that l, LAMBERT SCHMDT, acitizen of the United States, and a resident ot the borough oi Brooklyn,county ot Kings, city and State ot New York, have invented certain newand useitul improvements in Telephone Apparatus, ot which the 'Followingis a specification.

rlhis invention relates to telephone apparatus and more particularly, toa loud speaking' receiver for use in connection with apparatus employedfor the purpose ot establishing wireless telephonie communication.

Generically considered, it is the primary object and purpose ot mypresent invention to provide a receiver ot the magnet type which will behighly sensitive and instantly responsive tothe slightest variations inpolarity of the alternating currents coming `in over the line.

More particularly, my invention comprehends a radically new Form andconstruc tion oit the armature having a resiliently balanced suspensionin the bore of the This armature, in the preferred embodiment oit theinvention, is ot cylindrical torni and the pole shoes of the permanentmagnet are so related to the ends oi the armature at opposite sidesthereof that the magnetic tlu: acting* over a relatively small areaproduces an instantanoous responsive movement ot' the armature to theslightest pulsations ot the alternatingcurrents passing` through thetranslating coil,

As a detail item of improvement in instruments ot this character, lprovide a twospart armature and fulcrum n'ieans therefor which issecured and held in as sembled relation with the armature parts when thelatter are connected so that the armature and its fulcrum in tact,constitute a single unit and capable ot assemblage in operative positionby the mere insertion. oit the armature through the here ot the coilspool.

In `general. my present improvements provide a telei'ahone receiver asabove characterired,v which, though highly sensitive in its action,nevertheless composed oil? simply and substantially constructed elementswhich are capable of operative association in very compact relation andmay be coniined within a casino' of' appreciably smaller size than it ispossible to use in instruments Serial No. 570,869.

of' this character as heretofore constructed.

` il( ith the above and other objects in view, the invention consists inthe improved telephone receiver and in the iorrn, construction andrelative arrangement ol" its several parts as will be hereinafter moreiully described, illustrated in the accompanying drawings andsubsequently incorporated in the subjoined claims.

In the drawing: wherein l have illus trated one desirable and practicalembodiment of the invention and in which similar reference charactersdesignate correspond ing' parts throughout the several views,

Figure 'l is a rear elevation, the casing being removed to illustrateone embodiment oi my improved telephone receiver;

Figure Q is a section taken on the line 2 2 ot Figure l;

Figure is a view 'looking in a direction at right angles to Figure l;

Figure t is an enlarged detail section taken on the line Ll-4t ot Figure3, and

Figure 5 is a perspective view showing the several parts oit thearmature and its liulcrum in separated relation.

In the embodiment ot my invention which l have selected 'for purposes ofillustration. there is provided a permanent magnet 5 oi' theconventiomil til-shaped term. rl`o the inner opposed 'faces ot theparallel legs ot this permanent magnet the pole pieces 6 and i'respectively. are suitably secured. as by means of the screws 5%. Thesepole pieces at their relatively opposite ends are formed with flanges 9and lO respectively, projecting; inwardly `trom the attached arms otsaid pole pieces. Each flange is provided at its ends with theangfularly disposed shoes ll. and lf2 respectively, the shoes ot eachpole piece projecting to iards the shoes on the other pole piece and theopposed .shoes being positioned in the same plane.

The pole saoes il. and lf2 embrace the cylindrical spool i3. which isolf a suitable non-i'napgnetic material. oit the cylindrical.translating coil 141-,` The spool has the usual cylindrical bore l5 open:it its opposite ends.

@ne edge ot the pernianent magnet 5 is eu- ;raged against the inner taceot a '[ront plate 16 also ot a suitable non-macfnetic material and tothis plate the angular portion 9 oi' the pole piece (l is securelyriveted or otherwise lined.

llO

The armature as herein shown, comprises two complementary cylindricalsections 17 and 18 respectively. These armature sections have a maximumdiameter somewhat less than the diameter of the bore 15 of the coilspool. Each armature sect-ion has one end portion gradually reduced indiameter inwardly to its approximate center to thereby provide atapering portion 19. The armature section 17 at the end of its taperingportion is formed with an axially projecting threaded stud 2O adaptedfor engagement in a complementary threaded bore formed in the taperedend portion of the other armature section 18.

The ulcrum for the armatureconsists of two similar sheet metal parts 21,each of said parts having a sleeve 22 longitudinally split on one sideas at 23. At one end of the intermediate portion of the sleeve an ear 24is disposed at right angles to the axis of the sleeve and in opposedrelation to the end thereof, the spaced parts of the sleeve beingobliquely cut from the split 23 to the juncture of the ear 24 with thesleeve body, as indicated at 25. Each ear 24 has a central aperture 26to receive the threaded stud 20. The split sleeve of each fulcrum memberembraces the tapering portion 19 of each armature section adjacent itsinner smaller end. These sleeves are of greater external diameter thanthe maximum diameter oi the armature sections so that they will have africtional snug fit against the wall of the r bore in the coil spool.The inner diameters of the sleeves are also slightly greater than thediameters of the tapering portions of the armature sections around whichthey are engaged. Thus it will be understood that when the armature isinserted through the bore of the coil spool. it is supportedn in itsnormal position in coinciding axial relation with the spool bore solelyby means of the ears 24.

The opposite ends of the two-part armature project beyond the spool boreand are disposed between the complementary opposed shoes of the polepieces 6 and 7. The end faces of the pole shoes are concave, asindicated at 27, and are slightly eccentric with relation to thecylindrical armature so that in the normal position of the armature, theends of these concave faces are somewhat nearer to the periphery of thearmature than the central portion thereof. Greater responsiveness of thearmature to variations in the magnetic flux is thus produced since thelines of magnetic force are concentrated andmore equally distributed inradial diections with respect to the cylindrical armaure.

The end 0f the armature projecting from the inner end of the spool boreis provided with a reduced portion having a transverse groove 28 in oneside thereof to receive a the rod 29 and the end of the armature so thatsaid rod will always remain in a perpendicular position relative to thefront plate 16 in the arcuate movement of the armature end between thepole shoes. Preferably, I provide a split sleeve 30 which is adapted tobe engaged over the reduced end of the armature to protect the pivotalconnection with the rod 29 so that free pivotal action is assured. Therod 29 extends through a central opening in the plate 1G and is suitablyconnected to a non-magnetic disc 31 which may be of mica or othersuitable material, and is engaged at its marginal. edge upon an annularrib 32 formed upon the outer side of the plate 16.

lt will be understood that suitable bind' ing posts are mounted on thefront plate 16 and insulated from each other to which the ends of theelectromagnetic coiland the wires oi the telephonie receiving circuitare respectively connected.

The magnetic structure above described is enclosed within a casing 33 ofhard rubber or other suitable material which is exteriorly threaded atone end to receive t-he usual ear piece having the central openingtherein through which the sounds caused by vibrations ot the diaphragm31 are disseminated.

In the operation ot' the telephone instrument above described, it willbe understood that the alternatingr currents coming in over the line aretranslated by the electromagnetic coil and as long as the magnetic fluxof the pole pieces is equal, the cylindrical armature will remain in aAnormal position in'coinciding axial relation to the bore of the coilspool. The passage of fluctuating voice current-s over the receivingcircuit causes changes in direction and strength of the magnetic flux inaccordance with the variations in the voice currents and thus producesa. corresponding variation in the attraction and repulsion of thearmature relative to the pole shoes. The fulcrum members are preferablyproduced from finely tempered steel oli such gauge that the armaturewill instantly respond to the slightest variations in polarity of thealternating current. The two ears 24 being closely engaged with eachother constitute in effect. a single fulcrum support for the armature,the point of fulcrum being located at the juncture ofi these ears withthe sleeve members. The armature may thus vibrate without restraint inthe spool bore, such vibrations being transmitted through the medium ofthe pivotally connected rod to the flexible diaphragm which producessounds at the ear piece corresponding to the telephonie cur* rentstraversing the translating coil. As

the fulcrum members are rigidly secured to the cylindrical armature atits axial center, no binding action is possible, the actual fulcrumpoint of the armature being entirely free from frictional influences andthus materially increasing the responsiveness oit' the armature tominute changes in the iiuctuating voice currents.

I have found in practice that by provid iup; a 'Fulcrum means for thearmature as above described and eliminating the separate and independentarmature support secured to the pole shoes as heretofore used, thearmature may be employed in connection with the familiar cylindricalmagnetic coil which is less expensive and may be more easily wound thanthe oval or elongated type of coil. Also, it will be apparent that byreason oi the very simple and compact mounting and arrangement oic themagnetic coil and the armature as. herein disclosed, it is possible tohouse or enclose the magnetic construction within a casing), otunusually small dimensions.

lllhile primarily the present invention is designed lor use as atelephone receiver, it is obvious that the instrument might also be usedas a transmitter, since when the sound.

waves ot the voice are impressed upon the diaphragm the vibration of thelatter causes a movement ot the armature. This producesl electricalimpulses in the coil which will be vtransmitted over the line. Also, Ihave herein referred to the universal pivotal connectionv between therod 29 and the end of the cylindrical armature. This 'feature is not,however, claimed in detail as it forms the subject matter of a separateapplication for patent filed oi" even date herewith. In the presentapplication. however. I shall claim this connection with the diaphragmonly in a broad sense in conjunction with the arma` ture mounting.

The several other structural Jfeatures oi my improvement as aboveexplained are like-- wise susceptible ot embodiment in other alternatii'e structures and I accordingly reserve the privilege ofadopting' all such legitimate modiiications in the form, conw structionand relative arrangement ot' the several parts which may be iairlyconsidered as within the spirit and scope ot the inven tion as claimed.

I claim:

1. In telephonic apparatus, a. magnet coil, an armature extendingthrough the bore o'f said coil and an automatically balanced sus-Ypension means for the arma-ture having a part stationary with respect tothe armature and'frictionally engaged with the surface ot the coil bore,said means normally maintaining the armature in coinciding' axialrelation with the Coil.

2. In telephonie apparatus, a magnet coil. an armature adapted to bepositioned through said coil, and resilient 'Fulcrum means carried bythe armature to coact with the wall of the coil bore and maintain thearmature in automatically balanced suspension in said bore in coincidingaxial relation therewith.

3. .In telephonie apparatus, a cylindrical n'iagnet coil and its spool,a. cylindrical armature adapted to be positioned through the spool bore,and resilient iulcrum means carried by the armature and coacting withthe wall oit the spool bore to automatically maintain the cylindricalarmature in balanced suspension with its axis in coinciding relationwith the axis ot the spool.

4. In telephonie apparatus, a cylindrical magnet coil, a cylindricalarmature enclosed by said coil, and resilient tulcrum means for thearmature automatically acting' to maintain the armature in balancedsuspension in coincidingi axial rela-tion with the axis ot said coil,said tulcrumi means having a. part stationary with respect. to thearmature and renmvably engaged with the magnet coil.

In telephonie apparatus, a magnet coil, a. cylindrical armature enclosedby said coil, and resilient 'hilcruni mea-ns carried by the. armatureand having;- parts in fric-tional bearing` contact with the bore offsaid coil, said `tulcrum means maintaining the cylin d rical armature inbalanced suspension Within the coil and in coinciding axial relationtherewith i (3. In telephonie apparatus, a magnetic coil, an armature,and means carried by the armature wholly enclosed within said coil i'orsupporting` the armature in resiliently balanced suspension in normalcoinciding' axial relation with the coil.

7. In telephonie apparatus, a permanent magnet having opposed polepieces, a translating coil, an armature extending,- between the u'lagnetpole pieces, a diaphragm, vibration transmitting; means tor saiddiaphragm having a universal pivotal connection with said armature, andresilient fulcrum means constitutinga the sole support tor the varmatureand acting' to the same in balanced suspension in coincid ingr axialrelation with the coil in its normal position between `the magnet poles.

El. In telephonie apparatus, a permanentmagnet having opposed polepieces, a translating coil, an armature extending1 through said coil andprojectingF between the magnet pole pieces, a diaphragm, a vibrationtransmitting* member connected. at one ot its ends to the diaphragm andhaving a universal pivotal connection at its other end with saidarmature, and resilient iulcrum means for the ariinature whollycontained within the coil and acting; to automatically maintain saidarmature in balanced suspension in coincidingl axial relation to thecoil.

9. In telcphonic apparatus, a cylindrical automatically maintain magnetcoil and its spool, an armature adapted to be positioned through thebore of the coil spool, and means for maintainp ing the armature inresiliently balanced suspenslon 1n coinciding axial relation with the yyand a fulcrum member for the armature in- 15' cluding a partsurrounding the armature and friction-ally engaged with the wall of thespool bore and a relatively movable part fixed to the armature andsupporting the same in balanced suspension in normal coinciding axialrelation with the bore of the coil spool.

11. In telephonie apparatus, a cylindrical magnet and its spool, acylindrical armature adapted to be positioned through the spool bore,and a fulcrum member carried by said armature to extend within the spoolbore and frictionally coact with the wall thereof, said member having aresiliently movable part fixed to the armature to yieldngly maintain thearmature in balanced suspension in normal coinciding axial relation withthe bore of the coil spool.

12. In telephonie apparatus, a permanent magnet having opposed poleshoes, a translating coil, a cylindrical armature, fulcrum meanssupporting the armature in balanced suspension between the opposed endsof the pole shoes, and the end faces of said pole shoes being concavedin eccentric relation to the peripheral face of the armature.

13. In telephonie apparatus, ya permanent magnet having opposed poleshoes, a translating coil, a cylindrical armature, fulcrum l meanssupporting the armature in balanced suspension between the opposed endsof the pole shoes, the end faces of said opposed lshoes beingeccentrically concaved with respect to the peripheral surface of thearma- ,ture and having their opposite extremities disposed in closerproximate relation to the surface of the armature than the intermediateportions of said concave faces.

14. An armature for magnet telephones, and a cylindrical fulcrum memberfor the armature, said armature and the fulcrum member having coactingparts detachably securing the fulcrum member in fixed coaxial relationto the armature whereby said armature and the fulcrum member are com-,consisting of separable parts having complementary means whereby theymay be connected or disconnected, and a fulcrum member for the armaturehaving a portion adapted to be interposed between the armature parts andadapted to be engaged by the latter when said parts are connected tosecure the fulcrum member in fixed relation to the armature whereby thearmature and its fulcrum are combined in a single unit.

16. In a magnetic structure, an armature consisting of two separableparts provided at one of their ends with eoacting coupling means, and afulcrum member for the armature having a portion adapted to beinterposed between the opposed ends of the arv mature parts and upon thecoupling means of one of said parts whereby said portion of the fulcrummember is immovably fixed between the armature sections when the latterare connected.

17. In a magnetic structure, a cylindrical armature adapted to beinserted through the cylindrical bore of the coil spool` said armatureconsisting of two separable parts having connecting means and a fulcrummember for the armature having a portion adapted to be interposedbetween the armature parts to be engaged and ixedly held thereby whenthe armature parts are connected, said member being further providedwith a contractible part surrounding the armature and adapted forfrictional bearing Contact with the wall of the coil spool.

18. In a magnetic structure, a cylindrical. armature adapted to beinserted through the bore of a magnet coil spool, said armatureconsisting of two separable parts, and a resilient sheet metal fulcrummember for the armature having a contractible sleeve to frietionallyengage the wall of the coil spool and a resiliently yieldable part inspaced relation to one end of said sleeve adapted to be interposedbetween the armature parts and constituting a yieldable support for thearmature to maintain the latter in balanced suspension within the spoolbore.

19. In a magnetic structure, an armature consisting of separable partshaving coniplementary coupling means at one of their ends, and a pair offulcrum members each provided with a part adapted to be interposedbetween the armature parts and engaged upon the coupling means of one ofsaid parts and associated in fixed relation with the armature when theparts thereof are connected.

20. In a magnetic structure, a cylindrical armature adapted to beinserted through the bore of the magnet coil spool, said armatureconsisting of separable parts having complementary coupling means at oneof their ends, said end portions of the armature parts being externallyreduced in diameter, and a pair of fulcrum members each having a splitcontractible sleeve to surround the reduced portion of one of thearmature parts and each fulerum member being also provided With aresiliently movable armature supporting part in spaced relation to oneend of the sleeve, said supporting parts of the fulerum members adaptedto be interposed between the parts of the armature to be engaged andheld in iixed relation there- Wth when the armature parts are connectedwhereby said armature and the ulerum members are Combined in the form ofa single unit.

2l. An armature for magnet telephones, and a ulernm member ixed to thearmature and for insertion as a unit With the armature Within the boreof a magnet coil, said member having a part to eoaet With the surface ofsaid bore and removably support the armature in operative relation tothe magnet.

22. An armature for magnet telephones and a nlerum member fixed to thearmature for insertion as a unit therewith Within the bore of a magnetcoil, said member having a part engaging the Wall of the eoil bore Witha resilient frictional pressure to detachably retain the armature inoperative relation to the magnet.

23. An armature for magnet telephones and a :tulerum member for Saidarmature insertable as a unit therewith Within the bore of the magnetcoil, said member having a part fixed to the armature and a second partsurrounding the armature in spaced relation to said iiret named part andfriotionally eoaeting with the wall of the Coil bore to detaehablyretain the armature in its operative position.

In testimony that I claim the foregoing as my invention, I have signedmy name here under.

LAMBERT SCHMIDT.

